The present invention relates to a flooring product having a two-ply construction that is mounted to a base subfloor and, more particularly, to a bamboo or wood flooring plank with a bottom ply having a grain direction transverse to a grain direction of the top ply.
Various wood and bamboo flooring products are known in the art. Typically, wood flooring products, for example, are constructed of strips or planks that are either glued or nailed to a subfloor. The planks are typically constructed with a tongue on one side and a groove on an opposite side. When the flooring product is installed the tongue of one plank is mated with a groove on an adjacent plank to lock the planks together side-by-side to form an assembled floor.
Problems that may arise in such flooring products include warping, twisting and buckling of the flooring planks. For example, when the subfloor has irregularities and unevenness, the planks, having little flexibility, do not entirely conform to the irregularities and uneven portions of the subfloor, thus contributing to the above enumerated problems. Furthermore, flooring planks having longer lengths are more prone to warping, cupping and twisting not only after installation on the subfloor, but also prior to installation, thereby rendering the plank unusable. Thus, if the flooring plank has little or no flexibility, planks may be unusable for installation.
Previous attempts to create a flexible flooring plank have included a three-piece laminated wood floor having top, intermediate and bottom layers. The top and bottom layers have the same grain orientation while the intermediate layer located between the top and bottom layers has a grain orientation perpendicular to the grain orientation of the surrounding layers. The bottom layer includes a multiplicity of closely spaced-apart, cross-cut scores that extend across the width of the flooring plank and allow a degree of flexibility of the flooring plank. However, the cross-cut scores of this prior art flooring plank do not extend completely through the entire depth of the bottom layer to maintain a degree of rigidity of the overall flooring plank. Furthermore, since the top and bottom layers have the same grain orientation the additional third intermediate layer needs to have a perpendicular grain in order to provide stability in the transverse direction. Accordingly, the prior art utilizes a higher amount of material to construct the flooring plank while still possessing a significant degree of inflexibility of the bottom layer contacting the subfloor because the cut scores do not extend entirely through the bottom layer.
Other disadvantages of existing flooring include but are not limited to waste of materials, difficulty in materials selection, low yield, complicated processing technology, high consumption of adhesive, adjustable and/or detachable form of floor block and easy deformation.
Wu, U.S. Pat. No. 5,671,575, issued Sep. 30, 1997, entitled “Flooring Assembly”, discloses a flooring assembly comprising a required number of bottom foundation elements and top flooring elements having the same grain orientation. The top side of each foundation elements and the bottom side of each flooring elements contain corresponding grooves and face projections for joining the flooring elements and the foundation elements. The corresponding grooves and face projections on each flooring elements and foundation elements have a vertical surface at one side and inclined surface at the other side. A drawback of such arrangement is that the foundation elements extend completely throughout the entire flooring surface, thus requiring a higher amount of material to construct the flooring assembly. Another drawback of such arrangement is that the corresponding grooves and face projections, which contain vertical surface at one side and inclined surface at the other side, located on the bottom side of each flooring elements or on the top side of each foundation elements are rigidly joined or fixed, thus causing the flooring assembly to be rather inflexible, which tend to create problems including but not limited to warping, twisting, twisting, cupping and bucking of the flooring elements and/or foundation elements when, for example, the flooring surface contain irregularities or uneven portions.
Penland, U.S. Pat. No. 5,822,944, issued Oct. 20, 1998, entitled “Double Locking Flooring System for a Construction Site”, discloses a method and apparatus for constructing a two-layer flooring system for use at a construction or oil well drilling site by interlocking “mat units” having locking tabs and corresponding end locking slots. Penland only discloses a flooring system that should be “strong and sturdy enough to support heavy equipment, yet easily installed and removed,” but Penland does not teach how to use or construct a flooring system which conforms to or compensates for the irregularities or uneven portions on the flooring surface to create a floor with a relatively leveled or flat surface, nor does Penland teach how to minimize or prevent deformations including but not limited to shrinkage, expansion, warping, twisting and buckling, which frequently occur in commercial or home-use wood or bamboo flooring products as a result of changing weather conditions or frequent use.
Accordingly, there is a need for a flooring product having increased flexibility that also utilizes less material as well as possessing dimensional stability in both the longitudinal and traverse directions of the flooring plank. It is an objection of this invention to overcome the above-mentioned disadvantages by providing improved two-layer staggered combined flooring and a two-ply flooring having a cross-grain bottom ply.